A solid oxide cell (SOC) based on a ceramic ion conductor is a basis of the technique for electrochemically producing electricity or fuel at high temperature with high efficiency by using a solid oxide fuel cell (SOFC), a high-temperature solid oxide electrolysis cell (SOEC), a high-temperature co-electrolysis cell (Co-EC) or the like.
In these techniques, various hydrocarbon-based fuels are utilized in addition to hydrogen (the degree of freedom of fuel) for fuel cell operation, and at high-temperature co-electrolysis, water and carbon dioxide may be electrolyzed simultaneously to produce useful synthetic gas. To enhance such advantages and potentials, in addition to nickel (Ni) most frequently used at a fuel electrode, high-active catalysts (Pd, Ru, Rd, Fe, Co, Cu or the like) capable of promoting reactions and preventing carbon deposition need to be inserted and utilized.
In the existing technique, when a NiO—YSZ fuel electrode is prepared using a powder process, a catalyst such as Pd is mixed and then sintered, or a catalyst such as Pd is inserted into a sintered NiO—YSZ fuel electrode support solid oxide cell by means of infiltration or the like. In the former case, while the high-temperature sintering process is being performed, the catalyst may experience grain growth, which may reduce a surface area, decrease catalyst activity. In addition, inhomogeneous distribution of the catalyst may occur due to the imperfect powder mixing process. In the latter case, while the sintered solid oxide cell is being impregnated with a precursor solution containing a catalyst, the catalyst may not reach an interface of the electrolyte and the fuel electrode.
In addition, a catalyst layer may also be independently formed in the fuel electrode support of the solid oxide cell. However, basically, while a high-temperature sintering process is being performed, the catalyst grains may increase over a micron level to deteriorate catalyst activity, the catalyst substance may not be homogeneously inserted into the fuel electrode, and a physical or chemical defect may occur at the interface due to the difference in material from the fuel electrode.